CN111742587A

CN111742587A - Paging over open spectrum

Info

Publication number: CN111742587A
Application number: CN201980013539.1A
Authority: CN
Inventors: R·荣
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 2018-02-16
Filing date: 2019-02-18
Publication date: 2020-10-02
Anticipated expiration: 2039-02-18
Also published as: JP7132343B2; CN111742587B; WO2019158757A1; JP2021514161A; KR20200120725A; EP3753322A1; US11564201B2; EP3753322B1; US20210007076A1

Abstract

A method includes transmitting at least one synchronization signal burst (150) to a terminal (101) in a time-bounded channel access interval (405) of an open spectrum (409). The method further comprises transmitting at least one paging signal (4004, 4005) to the terminal (101) in a channel access interval (405) of the open spectrum (409).

Description

Paging over open spectrum

Technical Field

Various examples of the invention generally relate to paging a terminal using a paging signal communicated over an open frequency spectrum. In this regard, various examples relate specifically to open spectrum access policies.

Background

To facilitate efficient spectrum usage and high data rates, wireless communication may be conducted over unlicensed frequency bands. The unlicensed frequency band may be located in the open spectrum. Multiple operators or networks may share access to the open spectrum. In other words, access to open spectrum may not be limited to a single operator or network. In general, wireless communication over an open spectrum may involve procedures and limitations due to the possibility of multiple networks sharing the same spectrum. Such techniques are sometimes also referred to as clear channel assessment techniques, e.g., carrier sense multiple access/collision avoidance (CSMA/CA). Other techniques to ensure that multiple networks can share the same spectrum may include, but are not limited to, limits on maximum transmission percentage per time unit (limited transmission duty cycle), maximum transmission output power, and maximum channel occupancy time per transmission. The required techniques may depend on regulatory requirements for the open spectrum, which may vary depending on the particular spectrum and the geographical location of the device. Throughout the specification, any such process for implementing a desired technique imposed by multiple access restrictions to open spectrum is denoted as a "listen before talk" (LBT) process.

When performing an LBT procedure that attempts to transmit over an open spectrum, a network node may derive through the LBT procedure that it is currently unable to communicate with an intended recipient at an intended time, given the techniques required by multiple networks to share the spectrum. The network node may be limited by any transmission rules related to open spectrum sharing, and we refer to such unsuccessful transmission as LBT failure herein. When an LBT failure occurs, the sender may need to wait until the restrictions imposed by the sharing technique no longer prohibit communications. Such waiting may impose a timer or evaluate a limiting parameter, according to the example given above. Throughout the specification, this waiting is referred to as a backoff procedure. Thus, failure of the LBT procedure may cause communication delay.

On the other hand, for wireless communication, in order to limit energy consumption, idle mode operation is known. Here, the terminal (UE) does not maintain an active data connection with the network. To find the UE, paging is employed. Paging includes communication conveying one or more paging signals, typically including a paging indication and a paging message. Generally, paging is performed when the UE is operating in idle mode. The receiver of the modem of the UE may be configured to selectively receive the paging signal in the idle mode.

It has been observed that the latency for paging a UE increases significantly when one or more paging signals are communicated over the open spectrum. As described above, this may be due to the network node not being able to transmit paging signals at the expected time due to LBT failure and the associated backoff procedure, which may be related to Discontinuous Reception (DRX) of the UE.

Disclosure of Invention

Accordingly, there is a need for advanced techniques to access open spectrum for paging of UEs. In particular, there is a need for techniques that overcome or mitigate at least some of the above limitations and disadvantages.

This need is met by the features of the independent claims. The features of the dependent claims define embodiments.

A method includes transmitting at least one Synchronization Signal (SS) burst in a time-bounded channel access interval of an open spectrum. The at least one SS burst is transmitted to the terminal. The method also includes transmitting at least one paging signal in a channel access interval of the open spectrum. The at least one paging signal is transmitted to the UE.

Sometimes, an SS burst is also referred to as an SS block.

A method includes receiving at least one SS burst in a time-bounded channel access interval of an open spectrum. The at least one SS burst is received from the BS. The method also includes receiving at least one paging signal in a channel access interval of the open spectrum. The at least one paging signal is received from the BS.

A method of operating a terminal includes implementing a first reception attempt. The first reception attempt is over the open spectrum. The first reception attempt is for at least one synchronization signal burst. The method also includes implementing a second reception attempt. The second reception attempt is over the open spectrum. The second reception attempt is for at least one paging signal. The first and second reception attempts are implemented in a common, time-bounded channel access interval of the open spectrum.

A method includes transmitting and/or receiving (delivering) at least one SS in a time-bounded channel access interval of an open spectrum. At least one SS burst is delivered from a Base Station (BS) to a UE. The method also includes communicating at least one paging signal in a channel access interval of the open spectrum. At least one paging signal is communicated from the BS to the UE.

A computer program product or computer program comprises program code. The program code may be executable by at least one processor. Execution of the program code causes at least one processor to perform a method. The method includes transmitting at least one SS burst in a time-bounded channel access interval of an open spectrum. The at least one SS burst is transmitted to the terminal. The method also includes transmitting at least one paging signal in a channel access interval of the open spectrum. The at least one paging signal is transmitted to the UE.

A computer program product or computer program comprises program code. The program code may be executable by at least one processor. Execution of the program code causes at least one processor to perform a method. The method includes receiving at least one SS burst in a time-bounded channel access interval of an open spectrum. The at least one SS burst is received from the BS. The method also includes receiving at least one paging signal in a channel access interval of the open spectrum. The at least one paging signal is received from the BS.

A computer program product or computer program comprises program code. The program code may be executable by at least one processor. Execution of the program code causes at least one processor to perform a method. The method includes implementing a first reception attempt. The first reception attempt is over the open spectrum. The first reception attempt is for at least one synchronization signal burst. The method also includes implementing a second reception attempt. The second reception attempt is over the open spectrum. The second reception attempt is for at least one paging signal. The first and second reception attempts are implemented in a common, time-bounded channel access interval of the open spectrum.

A computer program product or computer program comprises program code. The program code may be executable by at least one processor. Execution of the program code causes at least one processor to perform a method. The method includes transmitting and/or receiving (delivering) at least one SS burst in a time-bounded channel access interval of an open spectrum. The at least one SS burst is communicated from the BS to the UE. The method also includes communicating at least one paging signal in a channel access interval of the open spectrum. The at least one paging signal is communicated from the BS to the UE.

A base station includes a control circuit. The control circuit is configured to perform a method. The method includes transmitting at least one SS burst in a time-bounded channel access interval of an open spectrum. At least one SS burst is transmitted to the terminal. The method also includes transmitting at least one paging signal in a channel access interval of the open spectrum. The at least one paging signal is transmitted to the UE.

A terminal includes a control circuit. The control circuit is configured to receive at least one SS burst in a time-bounded channel access interval of an open spectrum. The at least one SS burst is received from the BS. The control circuitry is further configured to receive at least one paging signal in a channel access interval of an open spectrum. The at least one paging signal is received from the BS.

A terminal includes a control circuit. The control circuit is configured to perform a first reception attempt for at least one SS burst over an open spectrum; a second reception attempt is conducted on the open spectrum for the at least one paging signal. The first and second reception attempts are implemented in a common, time-bounded channel access interval of the open spectrum.

A method of operating a terminal includes implementing a first reception attempt according to a timing schedule of a discontinuous reception cycle of the terminal. A first reception attempt is directed to at least one reference signal transmitted by a base station over an open frequency spectrum. The method also includes implementing the second reception attempt according to a timing schedule. The second reception attempts at least one paging signal transmitted on an open spectrum for the base station. The method further comprises the following steps: the backoff is selectively initiated for a further first reception attempt for the at least one SS burst and a further second reception attempt for the at least one paging signal according to a first result of the first reception attempt.

A computer program product or computer program comprises program code. The program code may be executable by at least one processor. Execution of the program code causes at least one processor to perform a method of operating a terminal. The method includes implementing a first reception attempt according to a timing schedule of a discontinuous reception cycle of the terminal. The first reception attempt is for at least one reference signal transmitted by the base station over an open frequency spectrum. The method also includes implementing the second reception attempt according to a timing schedule. The second reception attempts at least one paging signal transmitted on an open spectrum for the base station. The method further comprises the following steps: a backoff is selectively initiated for a further first reception attempt for the at least one reference signal and for a further second reception attempt for the at least one paging signal in dependence on a first result of the first reception attempt.

A terminal includes a control circuit. The control circuit is configured to implement the first reception attempt according to a timing schedule of a discontinuous reception cycle of the terminal. The first reception attempt is for at least one reference signal transmitted by the base station over an open frequency spectrum. The method also includes implementing a second reception attempt according to the timing schedule. The second reception attempt is for at least one paging signal transmitted by the base station over the open spectrum. The method further comprises the following steps: in accordance with a first result of the first reception attempt, a backoff is selectively initiated for a further first reception attempt for the at least one reference signal and for a further second reception attempt for the at least one paging signal.

For example, the reference signal may include a broadcast signal of the base station, an SS or SS burst, and/or a fixed preamble of a variable signal transmitted by the base station, and so on. Another implementation includes a channel sounding signal or a DL pilot signal, etc.

A method includes communicating at least one SS in a time-bounded channel access interval of an open spectrum. The at least one SS burst is communicated from the BS to the UE. The method also includes communicating at least one network access signal in a channel access interval of the open spectrum. The at least one network access signal is communicated from the BS to the UE and/or from the UE to the BS.

The at least one network access signal may facilitate connection of the UE to a network of BSs. For example, the at least one network access signal may facilitate establishing a data connection, e.g., a layer 3 bearer, etc., between the UE and the BS. For example, the at least one network access signal may facilitate transitioning from an idle mode of operation of the UE to a connected mode of operation of the UE. The at least one network access signal may include at least one of: a Random Access (RA) message of an RA procedure; RA preamble transmitted in UL RA message 1; DLRA message 2, e.g., for responding to UL RA message 1 and including a temporary identity of the UE; UL RA message 3, e.g., for establishing a layer 3 data connection; the DL RA message 4 is used, for example, to respond to the UL RA message 3.

For example, a 2-step or 4-step RA procedure may be employed.

By concatenating at least one SS and at least one network access signal into a common channel access interval, it is possible to end network access in a shorter duration, e.g., in fewer LBT attempts.

The UE includes control circuitry. The control circuitry is configured to receive at least one SS in a time-bounded channel access interval of an open spectrum. The at least one SS burst is transmitted from the BS to the UE. The control circuitry is further configured to communicate at least one network access signal in a channel access interval of an open spectrum. The at least one network access signal is communicated from the BS to the UE and/or from the UE to the BS.

The BS includes a control circuit. The control circuitry is configured to transmit at least one SS in a time-bounded channel access interval of an open spectrum. The at least one SS burst is communicated from the BS to the UE. The control circuitry is further configured to communicate at least one network access signal in a channel access interval of an open spectrum. At least one network access signal is communicated from the BS to the UE and/or from the UE to the BS.

It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without leaving the scope of the present invention.

Drawings

Fig. 1 schematically illustrates a network including a BS and a UE, in accordance with various examples.

Fig. 2 schematically illustrates a BS and a UE in more detail according to various examples.

Fig. 3 schematically illustrates an example implementation of a network as a cellular network, in accordance with various examples.

Fig. 4 schematically illustrates various operating modes of a UE in accordance with various examples.

Fig. 5 schematically illustrates receiver states of a UE associated with an operation mode and initiated according to a DRX cycle, according to various examples.

Fig. 6 is a signaling diagram illustrating paging of a UE in accordance with various examples.

Fig. 7 illustrates details of the paging of fig. 6 for communicating over open spectrum, in accordance with various examples.

Fig. 8 schematically illustrates allocation of time-frequency resources for SS bursts and paging signals, in accordance with various examples.

Fig. 9 schematically illustrates allocation of time-frequency resources for SS bursts and paging signals, in accordance with various examples.

Fig. 10 schematically illustrates allocation of time-frequency resources for SS bursts and paging signals, in accordance with various examples.

Fig. 11 schematically illustrates reception attempts by a UE in accordance with various examples.

Fig. 12 schematically illustrates reception attempts by a UE in accordance with various examples.

Fig. 13 schematically illustrates reception attempts by a UE in accordance with various examples.

Fig. 14 is a flow diagram of a method according to various examples.

Fig. 15 is a flow diagram of a method according to various examples.

Fig. 16 is a flow diagram of a method according to various examples.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the following description of the embodiments should not be taken in a limiting sense. The scope of the present invention is not intended to be limited by the embodiments described below or the accompanying drawings, which are illustrative only.

The figures are to be regarded as schematic representations and elements shown in the figures are not necessarily shown to scale. Rather, various elements are shown so that their function and general purpose are apparent to those skilled in the art. Any connection or coupling between functional blocks, devices, components or other physical or functional units shown in the figures or described herein may also be achieved through an indirect connection or coupling. The coupling between the components may also be established by a wireless connection. Functional blocks may be implemented in hardware, firmware, software, or a combination thereof. The same reference numbers in different drawings identify similar or identical components, functions, or acts.

Hereinafter, techniques of wireless communication are described. In particular, techniques are described that allow wireless communication over an open spectrum. Here, the time-frequency resources are generally not scheduled centrally. Therefore, in case of a failed transmission attempt, LBT and back-off are employed to avoid collisions between multiple devices attempting to access the open spectrum at the same time.

Techniques to facilitate operation of a UE in idle mode are described. In idle mode, the data connection is not maintained. This helps to reduce the energy consumption of the UE. This may be useful, in particular, for Machine Type Communication (MTC) or internet of things (IOT) devices, which typically have limited battery capacity. In addition, other devices may benefit from operation in idle mode. In idle mode, the UE may typically operate using a DRX cycle including an off duration and an on duration according to a respective timing schedule. During the off duration, a receiver of an interface of the UE may be in an inactive state. The receiver may not be suitable for receiving any data. Thereby, energy consumption can be reduced. The on-time duration is associated with a Paging Occasion (PO) during which the receiver operates in an active state suitable for receiving paging signals.

In particular, according to various examples, techniques are described that facilitate paging a UE in idle mode using paging signals communicated over open spectrum. In order to successfully page, three signals are typically required to be transmitted: first, one or more SSs, e.g., SS bursts; second, a paging indication; third, a paging message. In the following, reference is made to a paging signal comprising both a paging indication and a paging message. Each SS burst may include a plurality of SS blocks; each SS block may include a plurality of SSs, e.g., heterogeneous SSs, such as primary s (pss), Secondary SS (SSs), physical broadcast channel demodulation reference signal (PBCH-DMRS).

Various techniques are based on the discovery that it can be difficult to communicate SS bursts and paging signals over an open spectrum in such cases. That is, according to the reference implementation, three transmission attempts, including LBT, are required to succeed before all three signals can be transmitted. If any of these three transmission attempts fails, paging will be delayed due to the respective backoff. Although it is generally possible to define a PO that takes LBT related delay (e.g. due to backoff procedure) into account, especially in connection with DRX operation of the UE, there is a delay due to failed transmission attempts that is defined by a relatively long off duration of the timing schedule of the DRX cycle. This can result in significant delays in paging, for example, for MTC or IOT, the delay can be as long as minutes or even hours. This is because a PO may be missed while the next PO is only after the off duration of the DRX cycle.

From the third generation partnership project (3GPP) R1-1715582 contribution of conference RAN1#90-Bis, an implementation is known in which multiple SS bursts are sent to save LBT overhead. The reduction in LBT overhead increases the likelihood of successfully paging a UE within a single PO. However, the probability of paging failure in a single PO is high. The techniques described herein facilitate reliable paging within a single PO.

According to various examples, this is achieved by concatenating one or more SS bursts with one or more paging signals into a channel access interval of an open spectrum.

The channel access interval may limit the maximum time any given device may continuously access the open spectrum. Typically, the start of a channel access interval is defined by the start of a transmission over the open spectrum; the end time of the channel access interval (sometimes also referred to as maximum channel occupancy time, MCOT) is defined by a preset maximum duration according to the open spectrum access rules, i.e. regulatory requirements. The typical duration of the channel access interval may be in the range of 10ms-1 s.

Such a scheme facilitates a single transmission attempt to transmit both the SS for the UE acquiring synchronization and one or more paging signals, such as a paging indication and optionally a paging message. Thus, a single LBT procedure may be sufficient to complete paging for a UE. This facilitates paging in a single PO.

In order to embed these signals into the MCOT, the transmission can be extended to the frequency domain. For example, Frequency Division Duplexing (FDD) of multiple signals may be employed. For example, FDD of multiple SS blocks or even multiple SS bursts may be employed. Alternatively or additionally, FDD of multiple paging signals may be employed, e.g., FDD for paging indications and FDD for paging messages.

Generally, the amount of information required for a paging message may be greater than the amount of information required for a paging indication; similarly, the amount of information required for the paging indication may be greater than the amount of information required for the SS burst. Therefore, as the size of information to be transmitted increases, the bandwidth may increase at the end of the MCOT. This increase in required frequency bandwidth from SS bursts to paging information can therefore be seen as an asymmetric resource requirement, since the required transmission resources are varied in the frequency domain and are not symmetric along different transmission types.

Frequency diversity may be achieved by using FDD for SSs (e.g., for SS bursts). This may reduce the asymmetric resource requirements of the combined SS broadcast and paging transmission. This may help to efficiently occupy the open spectrum.

This is based on the following findings: the following trends may exist: asymmetric resource requirements result in occupying a small proportion of the physical time-frequency resource elements or resource blocks. Sometimes, individual resource elements or resource blocks cannot be addressed by scheduling, since the scheduling information is based on a collective addressing scheme for a plurality of resource elements or blocks, so-called Resource Block Groups (RBGs). A small fraction of the resource elements or blocks may not coincide with the RBGs. This is in contrast to the situation where there is a symmetric resource requirement that avoids a small proportion of the resource elements or blocks.

FDD may not need to be initiated for all SSs, but may be selectively initiated for SSs aligned with a PO (i.e., passing SSs within a PO). Additional SS or SS bursts may then be interleaved with the SS or SS bursts in the PO, the additional SS or SS bursts occupying a smaller bandwidth.

With such techniques, the UE can effectively resynchronize (i.e., reacquire timing synchronization) within a single PO (i.e., within a single instance of receiver activity) and identify possible pages. If the UE detects SS burst transmission, the apparatus may conclude in an in-coverage situation. The UE may then continue to listen for paging signals. Then, if paging is detected, the UE may continue a Random Access (RA) procedure, which may require LBT implemented by the UE.

Meanwhile, the UE can reliably detect unsuccessful transmission attempts by the BS to transmit the SS burst and the paging signal. This may be due to one or more SS bursts not being received. A customized backup procedure may then be implemented by the UE.

In particular, typically, a PO is associated with a certain duration of time that the UE expects the network to transmit paging signals. According to the reference implementation, in case of failure of transmission attempt due to LBT at the BS, the network and the UE wait for the next PO. Typically, the backoff duration is longer than the duration of the PO. Since PO periodicity is associated with DRX cycle timing scheduling, the time offset between subsequent POs typically corresponds to the off duration, i.e., seconds, minutes, or even hours. Thus, in the reference implementation, failure of a transmission attempt due to an occupied open spectrum (i.e., channel access by one or more other devices) can have a significant impact on latency. On the other hand, there are conceivable cases: the BS does not attempt to transmit any paging signal at all, only because no UE is paged. Then, the UE does not receive any corresponding signal. Therefore, the UE may erroneously assume that the transmission attempt of the BS fails; and in practice the BS never intends to transmit. This can be ambiguous and, depending on the particular implementation of the backup process, can result in wasted energy.

In the scenario described herein, the UE may detect a transmission attempt failure based on the absence of any signals (including SS) in the MCOT. Thus, the UE may conduct a first reception attempt for the at least one reference signal and may conduct a second reception attempt for the at least one paging signal. The reference signal may be any signal that the UE expects to be transmitted by the BS if the transmission attempt is successful. For example, an SS or SS burst may be an implementation of a reference signal. Another implementation includes a channel sounding signal or a DL pilot signal, etc. Then, depending on the result of the first reception attempt and the second reception attempt, different backup procedures may be taken. In one example, the UE may initiate a backoff in response to determining a failed transmission attempt based on a result of the first reception attempt. This may include, for example, a short off duration of the DRX cycle, or even keeping the receiver in the active state until the next PO.

Fig. 1 schematically illustrates a wireless communication network 100 that may benefit from the techniques disclosed herein. The network may be a 3GPP standardised network such as 3G, 4G-LTE or the upcoming 5G-NR. Other examples include point-to-point networks, such as Institute of Electrical and Electronics Engineers (IEEE) specified networks, such as the 802.11x Wi-Fi protocol or the bluetooth protocol. Further examples include 3GPP narrowband internet of things (NB-IoT) or enhanced machine type communication (eMTC) networks).

The network 100 includes a BS112 and a UE 101. A wireless link 114 is established between the BS112 and the UE 101. Wireless link 114 includes a DL link from BS112 to UE 101; and also includes the UL link from the UE101 to the BS 112. Time Division Duplexing (TDD), Frequency Division Duplexing (FDD), Space Division Duplexing (SDD), and/or Code Division Duplexing (CDD) may be employed to mitigate interference between the UL and DL. Similarly, TDD, FDD, SDD, and/or CDD may be employed to mitigate interference among multiple UEs (not shown in fig. 1) communicating over wireless link 114.

The UE101 may be, for example, one of: smart phones, cellular phones, tablets, laptops, computers, smart televisions, MTC devices, eMTC devices, internet of things devices, NB-IoT devices, sensors, actuators, and the like.

FIG. 2 schematically illustrates the BS112 and the UE101 in more detail.

BS112 includes a processor (CPU)1121 and an Interface (IF)1122, sometimes referred to as a front end. The IF 1122 includes a receiver and a transmitter. BS112 also includes memory (MEM)1125, such as a non-volatile memory. The memory may store program code that may be executed by the processor 1121. Thus, the processor 1121 and the memory 1125 form a control circuit. Execution of the program code may cause the processor 1121 to implement the following techniques: transmission over open spectrum including LBT operation, transmission attempt over open spectrum, backoff, SS transmission, paging signal transmission, and the like.

The UE101 includes a processor (CPU)1011 and an Interface (IF)1012, sometimes referred to as a front end. IF 1012 includes a receiver and a transmitter. The UE101 also includes a memory (MEM)1015, such as a non-volatile memory. Memory 1015 may store program code that may be executed by processor 1011. Thus, the processor 1011 and the memory 1015 form a control circuit. Execution of the program code may cause the processor 1011 to perform the following techniques: receiving over open spectrum including LBT operation, receiving an SS, receiving a paging signal, performing a reception attempt over open spectrum, performing LBT, etc.

Fig. 2 also illustrates SS 159. SS 159 is transmitted by BS112 and received by UE 101. SS 159 facilitates time synchronization between the reference clock of BS112 and the clock of UE 101. It is necessary that the UE101 be able to decode signals (e.g., paging signals) received from the BS 112. Time synchronization helps align the time-frequency resource grid used by the BS112 with the time-frequency resource grid used by the UE 101. Sometimes, SS 159 is clustered into SS bursts (not illustrated in fig. 2).

Fig. 3 schematically illustrates an example implementation of wireless network 100 in more detail. The example of fig. 3 illustrates a wireless network 100 according to the 3GPP 5G architecture. Details of the basic architecture are described in 3GPP TS 23.501 version 1.3.0 (2017-09). Although fig. 3 and other portions of the following description illustrate techniques in the 3GPP 5G framework, similar techniques may be readily applied to different communication protocols. Examples include 3GPP LTE4G and IEEE Wi-Fi technology.

The UE101 may connect to the network 100 via a Radio Access Network (RAN)111, typically formed by one or more BSs 112 (not illustrated in fig. 3). A radio link 114 is established between RAN 111 (and in particular one or more BSs 112 of RAN 111) and UE 101.

RAN 111 is connected to a Core Network (CN) 115. The CN115 includes a User Plane (UP)191 and a Control Plane (CP) 192. Bootstrap application data is typically routed via UP 191. To this end, an UP function (UPF)121 is provided. The UPF121 may implement router functionality. Application data may pass through one or more UPFs 121. In the scenario of fig. 3, the UPF121 serves as a gateway to a Data Network (DN)180, such as the internet or a local area network. Application data may be communicated between UE101 and one or more servers on DN 180.

The network 100 further comprises an access and mobility management function (AMF) 131; and a Session Management Function (SMF)132, a Policy Control Function (PCF)133, an Application Function (AF)134, a Network Slice Selection Function (NSSF)134, an authentication server function (AUSF)136, a Unified Data Management (UDM) 137. FIG. 3 also illustrates the protocol reference points N1-N22 between these nodes.

The AMF 131 provides one or more of the following functions: registration management, NAS termination, connection management, reachability management, mobility management, access authentication, and access authorization. The AMF 131 may negotiate NAS level security context with the UE 101. Please refer to 3GPP TS 23.501 version 1.3.0(2017-09), section 6.2.1. For example, if the corresponding UE101 operates in the disconnected mode, the AMF 131 controls CN-initiated paging of the UE 101. The AMF 131 may track the timing of the DRX cycle of the UE 101. The AMF 131 may trigger the BS112 of the RAN 111 to send a paging signal to the UE101, the UE101 for example in a tracking area to take into account UE mobility.

If the corresponding UE101 is operating in the connected mode, a data connection 189 is established by the AMF 131. To track the current mode of the UE101, the AMF 131 sets the UE101 to evolved packet System connection management (ECM) connected or ECM idle. During the ECM connection, a non-access stratum (NAS) connection is maintained between the UE101 and the AMF 131. NAS connections implement examples of mobility control connections. The NAS connection may be established in response to a page to the UE 101.

SMF 132 provides one or more of the following functions: session management including session establishment, modification and release, bearer establishment including UP bearers between RAN 111 and UPF121, selection and control of UPF, configuration of traffic flow steering, roaming functionality, termination of at least part of NAS messages, etc.

In this way, both AMF 131 and SMF 132 enable CP mobility management needed to support mobile UEs.

FIG. 3 also illustrates aspects related to data connections 189. A data connection 189 is established between UE101 and UP 191 of CN115 via RAN 111 and towards DN 180. A connection may be established with the internet or other packet data network. To establish the data connection 189, it is possible for each UE101 to perform a Random Access (RA) procedure, for example, in response to receipt of a paging signal. The servers of DN 180 may host services whose application data (sometimes referred to as payload data) is communicated over data connection 189.

The data connection 189 may include one or more bearers, such as a dedicated bearer or a default bearer. The data connection 189 may be defined at the Radio Resource Control (RRC) layer, e.g., layer 3 of the OSI model for layer 2 in general.

FIG. 4 illustrates aspects related to different modes 301-303 in which the UE101 may operate. Example implementations of the operational modes 301-303 are described in, for example, 3GPP TS 38.300 of release 15.0.

During the connected mode 301, the data connection 189 is established. For example, a default bearer and optionally one or more dedicated bearers may be established between the UE101 and the network 100. The receiver of the UE101 may be continuously operating in an active state.

To reduce power consumption, a transition may then be made from connected mode 301 to connected mode 302, which employs the DRX cycle of the receiver. The DRX cycles include an on duration and an off duration according to respective timing schedules. During the off duration, the receiver is not suitable for receiving data. The inactive state of the receiver may be initiated.

The timing schedule of the DRX cycle is synchronized between the UE101 and the BS112 so that the BS112 can align any DL transmissions (e.g., transmissions of application data) with the on duration of the connected mode DRX cycle. The data connection 189 remains established in the mode 302.

To achieve further power reduction, an idle mode 303 may be implemented. The idle mode 303 is again associated with the DRX cycle of the receiver of the UE 101. However, during the on-duration of the DRX cycle of the idle period 303, the receiver is only adapted to receive the paging indication and optionally the paging message. This may help limit the particular bandwidth that the receiver needs to monitor during the on duration of the DRX cycle in idle mode 303, for example. The receiver may not be suitable for receiving application data. This may help to further reduce power consumption, for example, assuming that compared to connected mode 302.

FIG. 5 illustrates aspects related to transitions between different modes 301-303. Fig. 5 illustrates aspects of employing a DRX cycle 370. Such techniques may be employed in various examples described herein with respect to the communication of paging signals.

First, the UE101 operates in the connected mode 301. This results in a high level of continuous power consumption, since the receiver is continuously operating in the active state 381. The active state 381 is associated with a certain power consumption. Then, in order to reduce power consumption, the connected mode 302 employing DRX is started. Here, the on-duration 371 and the off-duration 372 of the receiver selectively operating in the active state 381 and the inactive state 384 are illustrated.

To further reduce power consumption, next, an idle mode 303 is initiated. This is accompanied by releasing the data connection 189. Again, idle mode 303 employs a DRX cycle 370, which DRX cycle 370 includes an on duration 371 and an off duration 372 of a respective timing schedule 375. The on duration 371 in the idle mode 303 is associated with lower power consumption if compared to the on duration 371 of the connected mode 302, since in the idle mode 303 the capabilities of the receiver, which is now operating in the active state 382, may be reduced compared to the connected mode 302. While in the active state 382, in the idle mode 303, the receiver only expects to receive paging signals. The open duration 371 of the respective timing schedule 375 is aligned with the PO 202.

Fig. 6 is a signaling diagram. FIG. 6 illustrates aspects relating to communications between the UE101 and the BS 112. Fig. 6 illustrates aspects related to transmitting and/or receiving (conveying) paging signals 4004, 4005.

At 3001 (generally an optional block), a user data message 4002 is delivered. For example, the user data message 4002 may be communicated along the data connection 189, e.g., as part of a bearer or the like. The user data message 4002 comprises application data.

Then, there is no more data to be transferred between the UE101 and the BS 112. The transmit buffer is empty. This may trigger a timer. For example, the timer may be implemented at the UE 101. After a certain timeout duration, set according to the inactivity schedule 201, the receiver of the UE101 transitions 3002 from the active state 381 to the inactive state 384. This is done to reduce the power consumption of the UE 101. For example, prior to transitioning primary receiver 1351 to inactive state 384, data connection 189 may be released via appropriate control signaling (not illustrated in fig. 6). Timeout duration 201 is an example implementation of a triggering criterion for transitioning to inactive state 384; other trigger conditions are also possible. For example, a connection release message may be communicated.

This corresponds to a transition to the idle mode 303 (see fig. 4).

Multiple POs 202 are then implemented. The PO 202 may be in accordance with the on duration 371 of the DRX cycle 370.

At some point in time, BS112 transmits paging indicator 4004. UE101 receives paging indication 4004 at 3003. For example, the paging indication 4004 may comprise a temporary or static identity of the UE 101. The paging indication may indicate multiple UEs because the indication may be derived in an ambiguous manner from the UE's unique identity, such as the International Mobile Subscriber Identity (IMSI). Paging indication 4004 may include information regarding a Modulation and Coding Scheme (MCS) used to communicate paging message 4005 at 3004. The paging message 4005 may be communicated on a shared channel (e.g., a Physical Downlink Shared Channel (PDSCH)). The paging message may include RRC control data. Typically, the paging indicator 4004 and the paging message 4005 may be communicated on different channels. Paging message 4005 may be modulated and encoded according to the MCS indicated by paging indication 4004. Thus, the UE101 may be required to first receive the paging indication 4004 and then receive the paging message 4005. It is not mandatory to receive the paging indication 4004 and the paging message 4005 in the same PO.

Then, at 3005, a data connection 189 is established between the UE101 and the BS 112. This may include RA procedures and RRC establishment.

Finally, at 3006, a UL or DL user data message 4002, e.g., including payload data, is communicated using the newly established data connection 189.

In fig. 6, the UE101 activates its receiver in preparation for page reception in the PO 202. To do so, the UE101 typically needs to first identify the SS transmission. In fig. 6, SS burst transmission is not illustrated for simplicity. In 3gpp nr, the SS is included into an SS burst. For example, the SS blocks may include primary SS (pss) and Secondary SS (SSs) and broadcast channel (PBCH). Within a given SS burst, there may be several consecutive repetitions of the SS block. An SS burst may be defined by a certain time window (e.g., a 5ms time window). The maximum transmission bandwidth of each SS block may be 5104080 MHz, and the subcarrier spacing may be 1530120240 KHz. The SS burst set periodicity may be configured according to a set of 5,10,20,40,80,160 ms.

The scenario of fig. 6 may be combined with communication over the open spectrum. This is illustrated in fig. 7.

Fig. 7 is a signaling diagram. FIG. 7 illustrates aspects relating to communications between the UE101 and the BS 112. Fig. 7 illustrates aspects related to transmitting and/or receiving (conveying) paging signals 4004, 4005.

Fig. 7 specifically illustrates aspects of accessing open spectrum for paging. For example, the technique illustrated in fig. 7 may be employed in connection with the delivery of paging signals 4004, 4005 at 3003, 3004 of fig. 6.

At 3011, which is time aligned with PO 202, BS112 performs an LBT procedure. In other words, BS112 attempts to access the open spectrum. Thus, the signal level can be sensed over an open frequency spectrum. For example, the backoff 470 may be implemented if the signal level exceeds a threshold. In the scenario of fig. 7, the LBT procedure is implemented at 3011 according to timing scheduling 375 of the DRX cycle 370 implemented by the UE 101. The LBT procedure includes the BS112 performing a transmission attempt at the PO 202 coinciding with the on-duration 371 of the DRX cycle 370.

As illustrated in fig. 7, the transmission attempt fails and backoff 470 is initiated. Then, at 3012 (at the next PO 202 or still within the same PO 202), another LBT procedure is performed. At 3012, the transmission attempt is successful, so the BS112 transmits paging signals 4004, 4005 at 3013, 3014.

Other aspects regarding the actions of the UE101 are illustrated in FIG. 7. In the scenario of fig. 7, the UE101 implements reception attempts at 3015 and 3016 according to the timing schedule 375 of the DRX cycle 370. Since the transmission attempt at 3011 fails, the reception attempt at 3015 fails. The receive attempt at 3016 is successful.

In the following, techniques are described that help to distinguish between situations where no paging signal 4004, 4005 is received in a reception attempt due to: (I) the network does not page the UE101 and therefore does not even attempt to send paging signals 4004, 4005; (II) the network has attempted to send paging signals 4004, 4005, but it cannot because the transmission attempt failed. This facilitates a customized backup process at the UE 101. By avoiding blurring, energy consumption can be reduced.

Further, in the following, techniques are described that facilitate completing paging for a UE101 within the MCOT of the open spectrum.

The strategy to achieve this effect is illustrated in connection with fig. 8.

Fig. 8 illustrates such allocation of time-frequency resources for paging. In fig. 8, the allocation of time-frequency resources to SS bursts 150 and paging signals 4004, 4005 is illustrated. The time frequency resources are located on open spectrum 409.

The time-frequency resources may be defined by Orthogonal Frequency Division Multiplexing (OFDM) modulation including symbols and subcarriers. Atomic (atomic) element coding information is associated with a respective time-frequency resource element.

As illustrated in fig. 8, an SS burst 150 comprising a plurality of SSs 159 is communicated from BS112 to UE101 over an open spectrum. Further, paging signals 4004, 4005 are communicated from BS112 to UE101 over the open spectrum. As illustrated in fig. 8, the SS burst 150 and paging signals 4004, 4005 are communicated in a common MCOT 405. The allocation time-frequency resources are allocated separately. Thus, if the transmission attempt of the LBT procedure is successful, all signals 150, 4004, 4005 may be communicated within a single MCOT 405. Since only a single MCOT is required, the chances of completing paging quickly are increased compared to the case where multiple MCOTs are required due to poor time-frequency resource allocation.

Fig. 9 illustrates allocation of time-frequency resources for paging. Fig. 9 corresponds generally to fig. 8.

In the scenario of fig. 9, frequency division multiplexing is used to communicate multiple SS bursts 150. Thus, frequency diversity may be facilitated for synchronization of the UE101 with the BS 112. This generally increases the likelihood of successful reception of the paging signals 4004, 4005.

Alternatively or in addition to this frequency division multiplexing approach, time division multiplexing may also be used to communicate multiple SS bursts 150 if the length of the MCOT405 allows.

For example, the duration of the MCOT405 may be determined, for example, according to regulatory requirements of the open spectrum. The frequency reuse factor for frequency division multiplexing may then be selected based on this determination of the duration of the MCOT 405.

In the case of fig. 9 and 9, at least one SS burst 150 is communicated in the first portion 411 of the MCOT 405. Paging signals 4004, 4005 are conveyed in a second part 412 of the MCOT405, which is disposed after the first part 411. At least one SS burst 150 is communicated using bandwidth 451 and paging signals 4004, 4005 are communicated using bandwidth 452. In general, bandwidth 451 may be different from bandwidth 452. Since more information is typically transmitted in paging signals 4004, 4005, there is a tendency for bandwidth 452 to be greater than bandwidth 451; however, depending on the frequency reuse factor of the frequency division multiplexing used to transmit the plurality of SS bursts 150 (as illustrated in fig. 9), the difference may disappear or may be small. This helps to avoid resource allocation asymmetry between the first part 411 and the second part 412. This may help to efficiently occupy the open spectrum.

Furthermore, to limit the control signaling overhead that results from communicating multiple SS bursts, for example, by using frequency division multiplexing, a bandwidth that is adjusted to the delivery allocation of SS bursts may be employed. This situation is illustrated in fig. 10.

Fig. 10 illustrates allocation of time-frequency resources for paging and synchronization. In the scenario of fig. 10, the SS bursts 150 and paging signals 4004, 4005 are communicated according to the timing schedule 375 of the DRX cycle 370 of the UE101, i.e., at the PO 202.

In the scenario of fig. 10, implementing the bandwidth 451 for communicating the SS burst 150 at the PO 202, i.e., according to the timing schedule 375 of the discontinuous reception cycle 370, is implemented as in fig. 9. However, additional SS bursts 150A using smaller bandwidth 453 are passed between POs 202. For example, SS 159 included in SS burst 150 may be the same as or correspond to SS 159 included in SS burst 150A. As illustrated in fig. 10, the repetition rate of SS burst 150A may be greater than the repetition rate of communication signal burst 150.

The scheme of fig. 10 limits the control signaling overhead; while also facilitating low latency paging.

In the scenarios of fig. 8-10, the paging signal communicated in the MCOT405 includes a paging indication 4004 and a paging message 4005 (see fig. 6 and 7). Paging message 4005 is sent after paging indicator 4004. In general, low latency paging may already be facilitated if only the paging indication 4004 is communicated with at least one SS burst 150 in the MCOT 405. Then two LBT procedures may be required, but this still reduces the time required until paging is completed compared to the reference implementation.

If the MCOT405 includes multiple paging signals 4004, 4005, then the signals may be communicated using at least one of frequency division multiplexing and time division multiplexing, e.g., depending on the duration of the MCOT 405.

Further, as illustrated in fig. 8-10, at least one SS burst 150 and one or more paging signals 4004, 4005 are communicated in adjacent time-frequency resources. Thus, spectrum utilization may be high; this facilitates paging to be completed within one or only a few MCOTs 405. In the case of adjacent time-frequency resources, no symbols may be set between the at least one SS burst 150 and one or more paging signals 4004, 4005.

Fig. 11 illustrates allocation of time-frequency resources for paging and synchronization. In the scenario of FIG. 11, the SS burst 150 and paging signals 4004, 4005 are communicated according to the timing schedule 375-1 of the DRX cycle 370 of the UE101, i.e., at the PO 202.

Fig. 11 illustrates aspects relating to UE actions. Specifically, at 3101, the UE performs a reception attempt 471 of the at least one SS burst 150 and further performs a reception attempt 472 of the at least one paging signal 4004, 4005. Here, the receive attempt 471 is temporally aligned with the first portion 411 of the MCOT 405. The receive attempt 472 is temporally aligned with the second portion 412 of the MCOT 405.

Based on the result of the reception attempt 471 and, optionally, the result of the reception attempt 472, the backoff 470 is activated or deactivated (optionally activated). The backoff 470 enables further reception attempts 471, 472 after the backoff duration. By considering the result of the reception attempt 471, a reliable distinction can be made between failure of the transmission attempt of the LBT procedure at the BS112 on the one hand and the lack of network paging on the other hand.

In the example of fig. 11, both reception attempts 471 and 472 have a positive result at 3101, i.e., the UE101 is able to receive at least one SS burst 150 and at least one paging signal 4004, 4005. This implies that the transmission attempt of the LBT procedure at the BS112 also gets a positive result. Based on the result of the receive attempt 471 and the result of the receive attempt 472, the close duration 372 is then initiated. Specifically, at 3101, paging is not directed to the UE101, but to other UEs. Thus, the UE101 does not transition to the

connected mode

301, 302, but rather initiates the off duration 372 of the DRX cycle 370. The UE101 continues to operate in the disconnected mode 303 because it is not being paged.

At the next PO 202, at 3102, the UE101 again implements receive

attempts

471, 472. Both the reception attempt 471 and the reception attempt 472 fail, i.e. the respective result is negative. Failure to receive the attempt 471 triggers a start backoff 470 (see fig. 7). This is due to the following findings: a positive result of a transmission attempt by BS112 will result in the transmission of at least one SS burst 150, even in the absence of any network page. However, since the reception attempt 471 targeted at the at least one SS burst 150 also fails, it may be concluded that: due to the failed transmission attempt, BS112 implements backoff 470.

After the backoff 470, the UE101 again performs reception attempts 471, 472 at 3103, this time with a positive result. At 3103, at least one paging signal 4004, 4005 indicates paging for the UE101, which UE101 subsequently transitions to the connected mode 301, 302 (not illustrated in FIG. 11).

In the scenario of fig. 11, backoff 470 includes starting a backoff timer. 3102 and 3103 are part of the same PO 202. Specifically, between receive

attempts

471, 472 at 3102 and receive

attempts

471, 472 at 3103, the receiver of UE101 is continuously operating in active state 382. In other words, the back-off timer duration is shorter than the on-duration 371. This is possible because the duration 406 between adjacent MCOTs 405 (also typically defined by regulatory requirements of the open spectrum 409) is shorter than the on-duration 371. In this case, the timing schedule 375-1 of the DRX cycle 370 need not be modified. In other examples, it may be preferable to modify the timing schedule of the DRX cycle 370. This situation is illustrated in connection with fig. 12.

Fig. 12 illustrates allocation of time-frequency resources for paging and synchronization, the time-frequency resources being located on open spectrum 409. In the scenario of fig. 12, the SS burst 150 and paging signals 4004, 4005 are communicated according to the timing schedule 375-1 of the DRX cycle 370 of the UE101, i.e., at the PO 202.

Fig. 12 illustrates aspects relating to UE actions. The situation of fig. 12 corresponds substantially to the situation of fig. 11. However, in the scenario of FIG. 11, timing schedule 375-1 of DRX cycle 370 is modified to obtain timing schedule 375-2. Thus, in response to failure of receive attempt 471 at 3112, timing schedule 375-2 is started and timing schedule 375-1 is deactivated. Timing schedule 375-2 includes a shorter close duration 372 than timing schedule 375-1.

For example, the close duration 372 of timing schedule 375-1 may correspond to an integer multiple of the close duration 372 of timing schedule 375-2. For example, timing schedule 375-1 may facilitate power consumption reduction by extending the off duration 372 in accordance with a so-called enhanced DRX cycle as compared to a (non-enhanced) DRX cycle.

As illustrated in fig. 12, in response to failure of the reception attempts 471, 472 at 3112, the shutdown duration 372 is initiated, i.e., the receiver of UE101 transitions to the inactive state 384 (see fig. 5). Because both the reception attempt 471 and the reception attempt 472 fail, a conclusion can be made: the transmission attempt at BS112 fails.

Fig. 13 illustrates allocation of time-frequency resources for paging and synchronization, the time-frequency resources being located on open spectrum 409. In the scenario of fig. 13, the SS burst 150 and paging signals 4004, 4005 are communicated according to the timing schedule 375-1 of the DRX cycle 370 of the UE101, i.e., at the PO 202.

Fig. 13 illustrates aspects relating to UE actions. The situation of fig. 13 generally corresponds to the situation of fig. 12. In the scenario of fig. 13, at 3121, the receive attempt 471 succeeded, but the receive attempt 472 failed. This is due to the lack of network paging. However, since at least one SS burst 150 may be received as part of the reception attempt 471, the UE101 may conclude: the transmission attempt by BS112 is also successful. Then, because the receive attempt 471 is successful and the receive attempt 472 fails, the close duration 372 of the timing schedule 375 may be initiated.

Fig. 14 is a flow diagram of a method according to various examples. For example, the method of fig. 14 may be implemented by the

control circuits

1121, 1125 of the BS 112. Alternatively or additionally, the method of FIG. 14 may be implemented by the

control circuitry

1011, 1015 of the UE 101.

At optional block 5001, it is checked whether a PO is present. The PO may coincide with the on-duration of the timing schedule of the DRX cycle of the UE (see fig. 5, 6 and 10).

When a PO appears, the method begins with block 5002. At block 5002, at least one SS burst is communicated. For example, the plurality of SS bursts may be communicated using at least one of frequency division multiplexing and time division multiplexing. At block 5002, the BS may transmit at least one SS burst, and/or the UE may receive at least one SS burst.

Next, at block 5003, at least one paging signal is communicated. For example, a paging indication and/or a paging message may be communicated (see fig. 6 and 7). At block 5003, the BS may transmit at least one paging signal, and/or the UE may receive at least one paging signal.

Blocks

5002 and 5003 may include a transmission attempt by the BS and a reception attempt by the UE.

Blocks

5002, 5003 may be performed within a common MCOT of the open spectrum. Thus, at least one SS burst of block 5002 and at least one paging signal of block 5003 may be concatenated into a common MCOT (see fig. 8 and 9).

At optional block 5004, at least one additional SS burst is communicated. At least one additional SS burst of block 5004 is delivered at a time offset from any PO. Thus, if it is determined at block 5001 that there is no PO, at least one additional SS burst of block 5004 is also passed. For example, the at least one additional SS burst of block 5004 and the at least one SS burst of block 5002 may allocate different bandwidths on the open spectrum (see fig. 10).

Fig. 15 is a flow diagram of a method according to various examples. For example, the method of FIG. 15 may be implemented by the

control circuitry

1011, 1015 of the UE 101.

The method of fig. 15 may be interrelated with the method of fig. 14.

Block 5051 corresponds to block 5001 of fig. 14.

Block 5052 corresponds to block 5002 of fig. 14. If it is determined at block 5051 that a PO exists, a first receive attempt is conducted at block 5052. Implementing the reception attempt may include listening for one or more reference signals on the open spectrum.

Block 5053 corresponds to block 5003. At block 5053, a second reception attempt for the at least one paging signal is implemented.

In the case of fig. 15, if there is no PO, no reception attempt is performed. For example, the respective receiver may then operate in an inactive state (see fig. 5).

By implementing the first and second reception attempts in

blocks

5052, 5053, a distinction may be made between failure of a transmission attempt and lack of network paging in one aspect. This situation is illustrated in more detail in fig. 16.

Fig. 16 is a flow diagram of a method according to various examples. For example, the method of FIG. 16 may be implemented by the

control circuitry

1011, 1015 of the UE 101.

Block 5011 corresponds to block 5001 of fig. 14.

If it is determined at block 5011 that there is a PO, at block 5012, a timed scheduled on duration for the DRX cycle is initiated. This may include operating a receiver of the UE in an active state (see fig. 5) in which it is adapted to receive paging signals.

Block 5013 corresponds to block 5052 of fig. 15. As shown in fig. 15, here implemented by a receive attempt for one or more SS bursts.

Block 5014 corresponds to block 5053 of fig. 15.

At block 5015, a determination is made as to whether the first receive attempt has a positive result. For example, it may be checked whether at least one SS burst has been received at block 5013. At block 5015, if the first reception attempt is determined to be successful, block 5016 is performed.

At block 5016, a determination is made as to whether the second reception attempt was successful. For example, it may be checked whether at least one paging signal has been received at block 5014.

If it is determined at block 5016 that the second reception attempt of block 5014 has a positive result, at block 5017, it is checked whether the page is for the UE. For example, one or more UE identities included in the corresponding paging signal may be compared with the UE identity of the subject UE.

If it is determined at block 5017 that the network is attempting to page the UE, block 5022 is performed. At block 5022, a transition to connected mode is implemented (see fig. 4), for example by means of an RA procedure.

If it is determined at block 5017 that the network has not attempted to page the UE, at block 5018, the off duration of the DRX cycle is initiated. This may correspond to operating the receiver of the UE in an inactive state (see fig. 5). Similarly, if the second reception attempt is determined to be unsuccessful at block 5016, block 5018 is performed because the network has not paged any UEs.

If the first reception attempt is determined to be unsuccessful at block 5015, a backoff is initiated at block 5019. At block 5019, a backoff (also sometimes referred to as an LBT backoff) is implemented. As a general rule, different policies may be employed to implement backoff. One strategy includes starting a back-off timer. Another strategy, as illustrated in fig. 16, includes initiating another timing schedule for the DRX cycle at block 5020. At block 5021, it is checked whether an off duration of another timing schedule of a current start of a DRX cycle is shorter than a backoff. In the affirmative, the off duration of the now initiated additional timing schedule is initiated in block 5018; otherwise, the back-off timer may be started without starting the off duration of the DRX cycle; block 5013 may then be re-executed within the same PO.

In summary, techniques have been described to limit the impact of LBT for open spectrum communications on paging. In some examples, one or more SS bursts and one or more paging signals may be concatenated into the MCOT of the open spectrum. In further examples, the network node may alternatively or additionally conclude via an LBT procedure: which is currently unable to communicate with the intended receiver at the intended time. This is called LBT failure. A backup procedure may then be triggered.

The various techniques described herein are based on the following findings: the SS design for operation on unlicensed spectrum may be standalone or may be based on operation on licensed bands by the 3GPP NR. However, due to certain spectral characteristics and regulatory requirements, e.g. uncertain channel availability due to LBT, certain aspects need to be further considered. In terms of access rules, for example, the transmission bandwidth of SS blocks and RA signals may in many cases be narrower than the nominal channel bandwidth on the unlicensed band. Thus, the design or allocation of the transmission in the frequency domain may be tailored for this purpose.

In terms of channel access, it may be useful to reduce LBT overhead from control signaling. This can be achieved by using the MCOT to send control signals (network access signals) for initial access (e.g., SS, RA preamble, and RA Msg2/3/4) in a continuous manner.

Various techniques are based on the following findings: due to various channel access requirements, modifications may be required when applying the NR control signal design of the licensed band to the open spectrum.

Some of the techniques described herein relate to control signaling design, e.g., SS burst transmission for transmission over an open spectrum, where channel contention and channel occupancy time are taken into account. Multiplexing SS bursts with other transmissions, such as, for example, application data or network access signals on PDSCH, may be related to signaling bandwidth aspects and achieve LBT overhead reduction. Also, reducing the number of RA steps (e.g., 2-step RA procedures) or ensuring transmissions related to RA procedures may help reduce the occurrence of RA failures due to LBT failures.

The techniques described herein customize the design of control signaling for transmission over the open spectrum for channel access rules.

In summary, the following examples have been described:

example 1. a method of operating a base station (112), the method comprising:

-transmitting at least one synchronization signal burst (150) to the terminal (101) in a time-limited channel access interval (405) of an open spectrum (409), and

-transmitting at least one paging signal (4004, 4005) to the terminal (101) in the channel access interval (405) of the open spectrum (409).

Example 2. a method of operating a terminal (101), the method comprising the steps of:

-performing a first reception attempt (471) for at least one synchronization signal burst (150) over an open frequency spectrum (409), and

-performing a second reception attempt (472) for at least one paging signal (4004, 4005) over the open spectrum (409),

wherein the first reception attempt (471) and the second reception attempt are implemented in a common, time-bounded channel access interval (405) of the open spectrum (409).

Example 3. the method of example 2, further comprising:

-in dependence on a first result of the first reception attempt (471): selectively initiating a backoff (470) for a further first reception attempt (471) for the at least one synchronization signal burst (150) and for a further second reception attempt (472) for the at least one paging signal (4004, 4005).

Example 4. according to the method of example 3,

wherein if the first reception attempt (471) fails, a backoff (470) is activated,

wherein backoff (470) is not activated if the first reception attempt (471) is successful.

Example 5. according to the method of example 3 or 4,

wherein the first reception attempt (471) and the second reception attempt (472) are carried out according to a timing schedule (375, 375-1) of a discontinuous reception cycle (370) of the terminal (101),

wherein, the method also comprises the following steps:

-in dependence on the first and second results: selectively initiating an off-duration (372) of the discontinuous reception cycle (370).

Example 6. according to the method of example 5,

wherein the shutdown duration (372) is initiated at least in case the first reception attempt (471) is successful and the second reception attempt is failed.

Example 7. according to the method of any one of examples 3 to 6,

wherein the backoff (470) comprises starting a backoff timer.

Example 8. according to the method of any one of examples 3 to 7,

wherein the backoff (470) comprises another timing schedule (375-2) to initiate the discontinuous reception cycle (370), the other timing schedule (375-2) comprising a shorter close duration (372) than the timing schedules (375, 375-1).

Example 9. the method of any of the preceding examples,

wherein the at least one synchronization signal burst (150) comprises a plurality of synchronization signal bursts,

wherein the plurality of synchronization signal bursts (150) are transmitted using frequency division multiplexing.

Example 10. the method of example 9, further comprising:

-determining a duration of the channel access interval (405), an

-selecting a frequency reuse factor for frequency division multiplexing based on the determination of the duration of the channel access interval (405).

Example 11. the method of any of the preceding examples,

wherein the at least one synchronization signal burst (150) is transmitted in a first portion (411) of the channel access interval (405) using a first bandwidth (451) of the open spectrum (409),

wherein the at least one paging signal (4004, 4005) is transmitted in a second portion (412) of the channel access interval (405) using a second bandwidth (452) of the open spectrum (409) that is different from the first bandwidth (451),

wherein the second part (412) is transmitted after the first part (411).

Example 12. the method of any of the preceding examples,

wherein the at least one synchronization signal burst (150) is transmitted using a first bandwidth (451) of the open frequency spectrum (409),

wherein, the method also comprises the following steps:

-transmitting at least one further synchronization signal burst (150A) to the terminal (101) using a further bandwidth (453) of the open spectrum (409),

wherein the further bandwidth (453) is smaller than the first bandwidth (451).

Example 13. the method of any of the preceding examples,

wherein the at least one paging signal (4004, 4005) comprises a plurality of paging signals (4004, 4005),

wherein the plurality of paging signals (4004, 4005) are transmitted using at least one of frequency division multiplexing and time division multiplexing.

Example 14. the method of any of the preceding examples,

wherein the at least one paging signal (4004, 4005) comprises a paging indication (4004), and

wherein the at least one paging signal (4004, 4005) optionally comprises a paging message (4005) associated with the paging indication (4004) and transmitted after the paging indication (4004).

Example 15. the method of any of the preceding examples,

wherein the at least one synchronization signal burst (150) and the at least one paging signal (4004, 4005) are transmitted according to a timing schedule (375, 375-1) of a discontinuous reception cycle (370) of the terminal (101).

Example 16. the method of any of the preceding examples,

wherein the at least one synchronization signal burst (150) and the at least one paging signal (4004, 4005) are transmitted in adjacent time-frequency resources.

An example 17. a base station (112), the base station comprising control circuitry (1121, 1125) configured to:

Example 18. the base station (112) of example 17,

wherein the control circuitry is configured to perform the method of any of examples 1 and 9-16.

An example 19. a terminal (101), comprising control circuitry (1011, 1015), the control circuitry configured to:

Example 20. the terminal (101) according to example 19,

wherein the control circuit (1011, 1015) is configured to perform the method according to any one of examples 2 to 16.

Although the invention has been shown and described with respect to certain preferred embodiments, equivalents and modifications will occur to others skilled in the art upon the reading and understanding of the specification. The present invention includes all such equivalents and modifications, and is limited only by the scope of the following claims.

For illustration, various scenarios have been described above in which one or more SS bursts and one or more paging signals are concatenated into a common MCOT of the open spectrum. In some cases, it may be sufficient to receive a single SS for time synchronization between the UE and the BS. In such a case, the techniques may be modified to concatenate one or more SS signals and one or more paging signals into a common MCOT.

To further illustrate, it is often possible to concatenate one or more paging signals and one or more reference signals transmitted by a BS into a common MCOT of the open spectrum. While SS or SS bursts are one possible implementation of one or more reference signals, in other implementations, other kinds and types of reference signals may be used. Although some reference signals may not be suitable for time synchronization, they may still cause the UE to fail to distinguish between the lack of paging and the transmission attempt of the BS.

For further illustration, while various techniques have been described with respect to concatenating one or more paging signals and one or more SS bursts into a common MCOT, similar techniques may be readily applied to concatenating other kinds and types of signals into a common MCOT. For example, one or more SS bursts and one or more network access signals may be concatenated into a common MCOT. For example, one or more of the network access signals may include an RA preamble or RA message 2. In some examples, one or more SS bursts and one or more application data messages may even be concatenated into a common MCOT. Such techniques are based on the following findings: by concatenating one or more signals into a common MCOT, the overall likelihood of multiple transmission attempts due to LBT failure may be reduced.

For further illustration, various scenarios for a 3GPP NR 5G network have been described above. Similar techniques may be readily applied to other kinds and types of networks.

Claims

1. A method of operating a base station (112), the method comprising:

2. A method of operating a terminal (101), the method comprising the steps of:

3. The method of claim 2, further comprising the steps of:

4. The method of claim 3, wherein the first and second light sources are selected from the group consisting of,

wherein, the method also comprises the following steps:

5. The method of claim 4, wherein the first and second light sources are selected from the group consisting of,

6. The method according to any one of claims 3 to 5,

wherein the backoff (470) is initiated if the first reception attempt (471) fails,

wherein the backoff (470) is not initiated if the first reception attempt (471) is successful.

7. The method according to any one of claims 3 to 6,

wherein the backoff (470) comprises starting a backoff timer.

8. The method according to any one of claims 3 to 7,

9. The method according to any one of the preceding claims,

10. The method of claim 9, further comprising the steps of:

-determining a duration of the channel access interval (405), an

11. The method according to any one of the preceding claims,

wherein the second part (412) is transmitted after the first part (411).

12. The method according to any one of the preceding claims,

wherein, the method also comprises the following steps:

wherein the further bandwidth (453) is smaller than the first bandwidth (451).

13. The method according to any one of the preceding claims,

14. The method according to any one of the preceding claims,

15. The method according to any one of the preceding claims,

16. The method according to any one of the preceding claims,

17. A base station (112) comprising control circuitry (1121, 1125) configured to:

18. The base station (112) of claim 17,

wherein the control circuitry is configured to perform the method of any of claims 1 and 9-16.

19. A terminal (101) comprising control circuitry (1011, 1015), the control circuitry being configured to:

20. The terminal (101) of claim 19,

wherein the control circuit (1011, 1015) is configured to perform the method of any one of claims 2 to 16.